Input/output unit, input/output method, and receiving unit

ABSTRACT

A switching portion of an IRD supplies a non-descrambled TS (transport stream) received from a front end portion or a descrambled TS received from a descrambler to a DVCR connected to an IEEE 1394 interface. In addition, data received from the DVCR is supplied to the descrambler.

TECHNICAL FIELD

The present invention relates to an input/output unit, an input/outputmethod, and a receiving unit. In particular, the present inventionrelates to an input/output unit, an input/output method, and a receivingunit suitable for use with an IRD (Integrated Receiver and Decoder) andan STB (Set Top Box) that receive digital broadcast data.

Related Art

As the number of satellites is increasing and facilities for digitalsatellite broadcasts are improving, digital satellite broadcasts arebecoming common.

In digital satellite broadcasts, digital data as broadcast programs areoften scrambled so as to charge subscribers for programs that they haveviewed and listened to and to prevent non-subscribers from viewing andlistening to the broadcast programs. When digital data is descrambledfor a subscriber, the IRD may store charging information.

When digital video data and digital audio data as broadcast programs areencoded corresponding to for example MPEG (Moving Picture Experts Group)standard and transmitted as an MPEG transport stream (hereinafterreferred to as TS), the IRD extracts transport packets (hereinafterreferred to as TS packets) of a desired channel (program) fromdescrambled data and supplies decoded picture and decoded sound to thesubscriber (user).

Recently, a system that allows a digital VTR (Video Tape Recorder) torecord digital broadcast data received from the IRD and the IRD todecode data reproduced by the VTR has been proposed.

In such a system, it is convenient to allow the IRD to output data thathas not been descrambled (non-descrambled data) and an external unit toinput data that has not been descrambled (non-descrambled data) or thathas been descrambled (descrambled data) to the IRD.

It may be desired that the descrambling process and the charging processbe performed by an external unit rather than the IRD. To do that,digital data that has not been descrambled should be output from the IRDto the external unit. When the external unit does not have an MPEGdecoder, the external unit should output descrambled data to the IRD.

Disclosure of the Invention

The present invention is made from the above-described point of view. Anobject of the present invention is to allow a receiving unit (such as anIRD) that receives digital data to flexibly input and output data.

An input/output according to one aspect of the invention is aninput/output unit for managing data that is input and output between areceiving unit and an external unit, the receiving unit having receivingmeans for receiving digital data that has been scrambled at least partlyand descramble means for descrambling the digital data, the input/outputunit comprising an input/output controlling means for supplying digitaldata that is received from the receiving means or descrambled data thatis received from the descramble means to the external unit and supplyingdata that is received from the external unit to the descramble means ofthe receiving unit, the descrambled data being digital data descrambledby the descramble means, and an interface between the input/outputcontrolling means and the external unit.

A receiving unit according to another aspect of the invention is areceiving unit, comprising a receiving means for receiving digital datathat has been scrambled at least partly, a descrambling means fordescrambling the digital data, an input/output controlling means forsupplying digital data that is received from the receiving means ordescrambled data that is received from the descramble means to anexternal unit and supplying data that is received from the external unitto the descramble means, the descrambled data being digital datadescrambled by the descramble means, and an interface between theinput/output controlling means and the external unit.

An input/output method according to a further aspect of the invention isan input/output method for inputting and outputting data between areceiving unit and an external unit, the receiving unit having receivingmeans for receiving digital data that has been scrambled at least partlyand descramble means for descrambling the digital data, the input/outputmethod comprising the steps of supplying digital data that is receivedfrom the receiving means or descrambled data that is received from thedescramble means to the external unit and supplying data that isreceived from the external unit to the descramble means of the receivingunit, the descrambled data being digital data descrambled by thedescramble means.

In the input/output unit, the input/output controlling means suppliesdigital data that is output from the receiving means or descrambled datathat is output from the descramble means to the external unit. Inaddition, the input/output controlling means supplies data that isoutput from the external unit to the descramble means of the receivingunit.

In the receiving unit, the input/output controlling means suppliesdigital data that is output from the receiving means or descrambled datathat is output from the descramble means to the external unit. Inaddition, the input/output controlling means supplies data that isoutput from the external unit to the descramble means of the receivingunit.

In the input/output method, digital data that is output from thereceiving means or descrambled data that is output from the descramblemeans is supplied to the external unit. In addition, data that is outputfrom the external unit is supplied to the descramble means of thereceiving unit.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an example of the structure of abroadcasting system according to an embodiment of the present invention;

FIG. 2 is a block diagram showing an example of the structure of an IRD5shown in FIG. 1;

FIG. 3 is a block diagram showing an example, of the structure of afront end portion 11 shown in FIG. 2;

FIG. 4 is a block diagram showing an example of the structure of adecode portion 13 shown in FIG. 2;

FIG. 5 is a schematic diagram showing the data structure of a transportstream;

FIG. 6 is a schematic diagram for explaining an extracting method for TSpackets of a predetermined channel;

FIG. 7 is a block diagram showing an example of the structure of acontroller 14 shown in FIG. 2;

FIG. 8 is a block diagram showing an example of the structure of aswitching portion 21 shown in FIG. 2; and

FIG. 9 is a table showing switching operations of switches 61 to 63.

BEST MODES FOR CARRYING OUT THE INVENTION

FIG. 1 shows an example of the structure of a broadcasting systemaccording to an embodiment of the present invention. In this example,the system is a logical aggregation of a plurality of units regardlessof whether or not such units are contained in one housing.

On the broadcast station side, a transmitting unit 1 stores digitalvideo data and digital audio data as broadcast programs in such a mannerthat they have been MPEG-encoded and scrambled. In addition, thetransmitting unit 1 forms a TS that contains digital data of a broadcastprogram and other necessary data, performs several processes such as anerror correcting process for the TS, and modulates for the resultantsignal by for example QPSK (Quadrature Phase Shift Keying) modulatingmethod. Thereafter, the transmitting unit 1 up-converts the modulatedsignal and transmits the resultant signal as a radio wave through anantenna (parabola antenna) 2. The transmitting unit 1 forms a TS ofwhich data of six broadcast programs has been multiplexed pertransponder.

The radio wave transmitted from the antenna 2 is received by a satellite3. A transponder (not shown) of the satellite 3 performs severalprocesses such as an amplifying process for the received radio wave andthen transmits the resultant signal as a radio wave. The radio wavetransmitted from the satellite 3 is received by an antenna (parabolaantenna) 4 of the user (subscriber). The radio wave received from theantenna 4 is down-converted and then supplied to an IRD 5 (receivingunit).

The IRD 5 selects a signal from the radio wave received from the antenna4. In other words, the satellite 3 has a plurality of transponders. Theantenna 4 receives radio waves transmitted from the plurality oftransponders. Thus, a plurality of radio waves are down-converted. Inother words, since the antenna 4 receives a plurality of radio waves,the IRD 5 selects one of radio waves transmitted from the plurality oftransponders corresponding to a channel selecting operation of the user.

In addition, the IRD 5 QPSK-demodulates a signal of the selected radiowave (namely, a signal that has been QPSK-modulated) and performsseveral processes such as an error correcting process for the resultantsignal as a TS. Thereafter, the IRD 5 descrambles the TS that has beenerror-corrected and extracts TS packets of the user selected channelfrom the descrambled TS. Next, the IRD 5 MPEG-decodes data of the TSpackets and supplies the resultant data as a picture to a monitor 6 (andthe resultant data as sound to a speaker (not shown)).

The IRD 5 is connected to a DVCR (Digital Video Cassette Recorder) 7 asan external unit corresponding to IEEE (Institute of Electrical andElectronics Engineers) 1394 standard that is a serial interfacestandard. When necessary, a TS that has been descrambled (descrambledTS) or that has not been descrambled (non-descrambled TS) can beexchanged with the DVCR 7. When the IRD 5 receives a descrambled TS fromthe DVCR 7, the IRD 5 MPEG-decodes the descrambled TS and outputs theresultant signal to the monitor 6. In contrast, when the IRD 5 receivesa non-descrambled TS, the IRD 5 descrambles the non-descrambled TS,MPEG-decodes the resultant signal, and then outputs the resultant signalto the monitor 6.

The DVCR 7 records data received from the IRD 5. In addition, the DVCR 7reproduces data and supplies the reproduced data to the IRD 5.

After having described a TS, when necessary, the IRD 5 performs aprocess for charging the user for the TS as a broadcast program (forexample, creating a subscriber program viewing/listening history). Theresultant charging information is transmitted to the transmitting unit 1through for example a public network 8. The transmitting unit 1 chargesthe subscriber for broadcast programs corresponding to the charginginformation.

FIG. 2 shows an example of the structure of the IRD 5 shown in FIG. 1.

Referring to FIG. 2, the IRD 5 is mainly composed of a receiving processportion 10 and a data interface 20. The receiving process portion 10 iscomposed of a front end portion 11, a descrambler 12, a decode portion,a controller 14, and a modem 15. The data interface 20 is composed of aswitching portion 21 and an IEEE 1394 interface 22. Individual blocksthat compose the receiving process portion 10 and the data interface 20are connected to each other through a control bus 16.

The front end portion 11 receives a signal through the antenna 4 andthen down-converts it. Thereafter, the front end portion 11 performs apredetermined receiving process for the signal that has beendown-converted and supplies the resultant signal as a TS (that has notbeen descrambled) to an input terminal IN1 of the switching portion 21.The descrambler 12 descrambles a non-descrambled TS received from anoutput terminal OUT of the switching portion 21 and supplies thedescrambled TS to the decode portion 13 and an input terminal IN2 of theswitching portion 21.

The decode portion 13 extracts TS packets corresponding to the userselected channel from the descrambled TS packets, MPEG-decodes theextracted TS packets, and outputs the resultant signal as a picture andsound. In addition, the decode portion 13 extracts TS packetscorresponding to control data from the descrambled TS packets receivedfrom the descrambler 12 and supplies the extracted TS packets to thecontroller 14 through the control bus 16.

The controller 14 performs various processes corresponding to thecontrol data received from the decode portion 13, a signal received froma remote controller (remote commander) operated by the user, and signalsreceived from blocks connected to the control bus 16. In addition, thecontroller 14 controls the front end portion 11, the descrambler 12, thedecode portion 13, and the IEEE 1394 interface 22 that compose the IRD 5through the control bus 16 corresponding to such signals.

The modem performs communication control for transmitting charginginformation and so forth to the transmitting unit 1 through the publicnetwork 8.

The switching portion 21 supplies a signal that is received from thefront end portion 11 through the input terminal INT1 to the descrambler12 through the output terminal OUT under the control of the controller14. In addition, the switching portion 21 supplies a non-descrambled TSthat is received from the front end portion 11 or a descrambled TS thatis received from the descrambler 12 to the DVCR 7 as an external unitthrough an input/output terminal IN/OUT and the IEEE 1394 interface 22.Moreover, the switching portion 21 supplies data that is received fromthe DVCR 7 through the IEEE 1394 interface 22 and the input/outputterminal IN/OUT to the descrambler 12 through the output terminal OUT.

The IEEE 1394 interface 22 communicates with the DVCR 7 corresponding tothe IEEE 1394 standard. Thus, the IEEE 1394 interface 22 transmits datareceived through the input/output terminal IN/OUT of the switchingportion 21 to the DVCR 7. In addition, the IEEE 1394 interface 22supplies data received from the DVCR 7 to the input/output terminalIN/OUT of the switching portion 21. In the embodiment shown in FIG. 2,the IEEE 1394 interface 22 has three input/output ports for externalunits. However, according to the present invention, the number ofinput/output ports of the IEEE 1394 interface 22 is not limited tothree.

A conventional IRD does not have a data interface 20. In theconventional IRD, an output signal of a front end portion 11 is directlysupplied to a descrambler 12. In contrast, according to the presentinvention, the IRD 5 has the data interface 20. In addition, an outputsignal of the front end portion 11 is supplied to the descrambler 12through the switching portion 21.

Next, the operation modes of the IRD 5 will be described.

When the user views and listens to a broadcast program (hereinafter, theoperation mode of the IRD 5 in this case is referred to as normal mode),he or she selects the channel of the broadcast program. In this case,the controller 14 detects a transponder that has transmitted a signalcorresponding to the selected channel and controls the front end portion11 through the control bus 16 to select the signal corresponding to therelevant transponder. The front end portion 11 receives signals from theantenna 4 and selects a signal of a frequency band under the control ofthe controller 14. In addition, the front end portion 11 performs apredetermined process for the received signal and supplies the resultantsignal as a TS to the input terminal IN1 of the switching portion 21.

In this case, the controller 14 controls the switching portion 21through the control bus 16 to output the signal received from the inputterminal IN1 through the output terminal OUT. Thus, the switchingportion 21 directly outputs the TS received from the front end portion11 through the input terminal IN1 to the descrambler 12 through theoutput terminal OUT under the control of the controller 14.

The descrambler 12 descrambles a scrambled TS received from theswitching portion 21 and supplies the descrambled TS to the decodeportion 13.

At this point, the controller 14 controls the decode portion 13 throughthe control bus 16 to decode packets of the user selected channel. Thedecode portion 13 extracts packets corresponding to the user selectedchannel from the descrambled TS packets received from the descrambler 12and then MPEG-decodes the extracted packets. Thus, a picture and soundof the broadcast program corresponding to the user selected channel areoutput to the monitor.

When a non-descrambled TS is output to the DVCR (hereinafter, theoperation mode of the IRD 5 in this case is referred to as thenon-descramble output mode), the controller 14 controls the switchingportion 21 through the control bus 16 to output the TS received from thefront end portion 11 to the IEEE 1394 interface 22.

The switching portion 21 supplies the TS received from the front endportion 11 through the input terminal IN1 to the IEEE 1394 interface 22through the input/output terminal IN/OUT under the control of thecontroller 14.

At this point, the controller 14 controls the IEEE 1394 interface 22through the control bus 16 to output data received from the switchingportion 21 to the DVCR 7. The IEEE 1394 interface 22 transmits anon-descrambled TS received from the switching portion 21 to the DVCR 7corresponding to the IEEE 1394 standard as a communication procedureunder the control of the controller 14.

In this case, the controller 14 transmits a record AV/C (AudioVisual/Control) command to the DVCR 7 through the control bus 16 and theIEEE 1394 interface 22. The DVCR 7 records a non-descrambled TS receivedfrom the IEEE 1394 interface 22 corresponding to the record AV/Ccommand. The DVCR 7 has an interface with the same function as the IEEE1394 interface 22. Since the interface of the DVCR 7 and the IEEE 1394interface 22 communicated through the IEEE 1394 standard, data andcommands are exchanged between the IRD 5 and the DVCR 7.

When a descrambled TS is output to the DVCR 7 (hereinafter, theoperation mode of the IRD 5 in this case is referred to as thedescramble output mode), the controller 14 controls the switchingportion 21 through the control bus 16 to output a signal received fromthe input terminal IN1 to the output terminal OUT and a signal receivedfrom the input terminal IN2 to the input/output terminal IN/OUT. Theswitching portion 21 directly outputs the TS received from the front endportion 11 through the input terminal IN1 to the descrambler 12 throughthe output terminal OUT under the control of the controller 14. Thedescrambler 12 descrambles the TS and supplies the descrambled TS to theinput terminal IN2 of the switching portion 21. The switching portion 21outputs the TS received from the descrambler 12 through the inputterminal IN2 to the IEEE 1394 interface 22 through the input/outputterminal IN/OUT.

As in the non-descramble output mode, the IEEE 1394 interface 22transmits a descrambled TS received from the switching portion 21 to theDVCR 7. The DVCR 7 records the descrambled TS.

When data recorded in the DVCR 7 is reproduced and supplied to the IRD 5(hereinafter, the operation mode of the IRD 5 in this case is referredto as the input mode), the controller 14 transmits a reproduction AV/Ccommand to the DVCR 7 through the control bus 16 and the IEEE 1394interface 22. The DVCR 7 reproduces data recorded therein correspondingto the reproduction AV/C command.

At this point, the controller 17 controls the IEEE 1394 interface 22through the control bus 16 to supply data received from the DVCR 7 tothe switching portion 21. The IEEE 1394 interface 22 receives datareproduced from the DVCR 7 (in this case, the data is a TS)corresponding to the IEEE 1394 standard as a communication procedureunder the control of the controller 14. Thereafter, the IEEE 1394interface 22 supplies the TS received from the DVCR 7 to theinput/output terminal IN/OUT of the switching portion 21.

The switching portion 21 outputs the TS received from the input/outputterminal IN/OUT to the descrambler 12 through the output terminal OUT.

When a TS received from the switching portion 21 has been scrambled, thedescrambler 12 descrambles the TS and supplies the descrambled TS to thedecode portion 13. In contrast, when a TS received from the switchingportion 21 has not been scrambled, the descrambler 12 directly suppliesthe TS to the decode portion 13. As in the normal mode, the decodeportion 13 MPEG-decodes the TS received from the descrambler 12.

The descrambler 12 determines whether or not a TS (TS packets) receivedfrom the switching portion 21 has been scrambled based on two bits ofscramble control information contained in a TS packet shown in FIG. 5(the scramble control information will be described later).

FIG. 3 shows an example of the structure of the front end portion 11shown in FIG. 2.

Signals received from the antenna 4 are supplied to a tuner 31. Thetuner 31 receives the signals from the antenna 4 and selects a signal ofa frequency band of a predetermined transponder corresponding to acontrol signal received from the controller 14 through the control bus16. The selected signal is supplied to a demodulating circuit 32. Thedemodulating circuit 32 QPSK-demodulates the signal received from thetuner 31 and supplies the resultant signal as a TS to an errorcorrecting circuit 33. The error correcting circuit 33 performs an errorcorrecting process for the TS received from the demodulating circuit 32and supplies the resultant signal to the input terminal IN1 of theswitching portion 21.

FIG. 4 shows an example of the structure of the decode portion 13 shownin FIG. 2.

A descrambled TS received from the descrambler 12 is supplied to a DMUX(demultiplexer) 41. The DMUX 41 extracts required TS packets withreference to a PID (Packet Identification) thereof and supplies theextracted TS packets to relevant RAMs (Random Access Memories) 42 to 45.

In other words, the DMUX 41 extracts a TS packet that containsinformation necessary for generating a clock signal (the information isfor example PCR (Presentation Clock Reference)) and supplies the TSpacket to the RAM 42. The DMUX 41 extracts TS packets that have videodata and audio data of a user selected channel (the TS packets have beenMPEG-encoded) and supplies the extracted TS packets to the RAM 43 andRAM 44, respectively. In addition, the DMUX 41 extracts a TS packet thathas information for controlling various portions and supplies theextracted TS packet to the RAM 45.

The remaining TS packets that have not been extracted by the DMUX 41 arediscarded.

The RAMs 42 to 45 store the relevant TS packets extracted by the DMUX41.

The clock generator 46 reads a TS packet from the RAM 42 and generates aclock signal based on the information contained in the TS packet. Theclock signal generated by the clock generator 46 is supplied to an MPEGvideo decoder 47, an MPEG audio decoder 48, and other relevant blocks.

The MPEG video decoder 47 and the MPEG audio decoder 48 read TS packetsfrom the RAMs 43 and 44, respectively. The MPEG video decoder 47 and theMPEG audio decoder 48 MPEG-decode video data and audio data that havebeen MPEG-encoded, respectively.

A microcomputer 49 reads a TS packet from the RAM 45 and extractscontrol data for controlling each block based on the informationcontained in the TS packet and supplies the control data to relevantblocks through the control bus 16.

FIG. 5 shows the data structure of a TS.

Referring to FIG. 5, a TS is composed of TS packets (the data length ofeach TS packet is 188 bytes).

The first four bytes (32 bits) of each TS packet are a so-called packetheader. The remaining 184 bytes are an adaptation field and a payload.Alternatively, the remaining 184 bytes are only a payload.

Since information contained in the packet header is defined in the MPEG2standard, only data required in the present invention will be brieflydescribed. A PID is placed in 13 bits from the 12-th bit to 24-th bit.The PID is used to identify the current TS packet. The PID is followedby a scramble control portion of two bits. The scramble control portionrepresents whether or not the payload has been scrambled. In addition,the scramble control portion represents the type of the payload. Asdescribed above, with reference to the scramble control portion, thedescrambler 12 determines whether or not (the payload of) the current TSpacket has been scrambled.

The PCR as information for generating the clock signal is placed at oneor a plurality of successive positions of the adaptation field.According to the MPEG2 standard, the PCR can be placed in at least oneposition of the adaptation field.

As described above, with reference to the PID contained in the currentTS packet, the DMUX 41 (see FIG. 4) extracts required TS packets. Next,with reference to FIG. 6, a method for extracting a TS packet thatcontains video data of a desired channel will be described.

A TS packet containing video data of a particular channel is assigned aunique PID corresponding thereto. Thus, to extract a TS packet of adesired channel, the value of the PID assigned to the packet isrequired. Consequently, a TS has a TS packet that contains additionalinformation table PSI (Program Specific Information) that represents therelation between channels and PIDs.

Examples of the PSI are a PAT (Program Association Table) and PMT(Program Map Table).

The PAT is assigned a predetermined constant value (0x00) (where 0xrepresents hexadecimal notation) as a PID. The PAT contains the PID ofthe PMT to be referenced for obtaining a TS packet corresponding to aparticular broadcast program number (channel).

In addition, the PMT contains a PID of a TS packet (video packet) ofvideo data of a broadcast program corresponding to a particular programnumber.

Thus, to extract a TS packet of video data of a particular channel, apacket whose PID is 0x00 (namely, a PAT) is received and then a PIDcorresponding to a program number assigned to the desired channel isdetected. Thereafter, a TS packet with the PID is received. Namely, thePMT is received. In addition, the PID is extracted from the PMT. Thus, avideo packet with the PID is received.

In reality, when a TS packet containing video data of a channel whosebroadcast program number “1” is extracted, the PAT represents that thePID of the PMT of the program number is “11”. When a TS packet with thePMT is received, the PID of a TS packet containing video data of thechannel whose broadcast program number is “1” is “p”. Thus, a TS videopacket whose PID is “p” is extracted.

The header of each TS packet shown in FIG. 5 is removed by the DMUX 41.The remaining TS packet is supplied to a relevant one of the RAMs 42 to45 (more accurately, the portion of the TS packet from which the headeris removed is supplied to a relevant one of the RAMs 42 to 45).

FIG. 7 shows an example of the structure of the controller 14 shown inFIG. 2.

An I/F (Interface) 51 connects the control bus 16 and an internal bus55. The I/F 51 supplies a signal received through the control bus 16 toa CPU (Central Processor Unit) 52 through the internal bus 55. Inaddition, the I/F 51 outputs control data received from the CPU 52through the internal bus 55 to a relevant block through the control bus16.

The CPU 52 performs various processes corresponding to a signal receivedfrom the I/F 51 through the internal bus 55. In addition, the CPU 52generates control data and supplies it to the I/F 51. The I/F 51 alsosupplies a signal corresponding to an operation of a remote controllerby the user to the CPU 52. The CPU 52 performs various processescorresponding to signals received from the I/F 51.

A ROM (Read Only Memory) 53 stores an IPL (Initial Program Loading)program, a boot strap program, and data. After the power of the IRD 5 isturned on or the IRD 5 is reset, the CPU 52 reads the programs and datafrom the ROM 53. Thus, the IRD 5 gets started.

A RAM 54 stores programs and data necessary for the operation of the CPU52 (the programs are OS (Operating System) and an application program).The ROM 53 is composed of for example a flash memory.

FIG. 8 shows an example of the structure of the switching portion 21shown in FIG. 2. As shown in FIG. 8, the switching portion 21 is mainlycomposed of a switcher 60 and a data parser portion 70.

The switcher 60 is composed of switches 61 to 63.

A terminal 61a of the switch 61 is connected to the input terminal IN1.Thus, a non-descrambled TS is supplied from the front end portion 11 tothe terminal 61 a of the switch 61 through the input terminal IN1. Aterminal 61 b of the switch 61 is connected to a terminal 63 b of theswitch 63. The switch 61 is connected to a terminal 62 b of the switch62 and the output terminal OUT. The switch 61 selects one of theterminals 61 a and 61 b under the control of the controller 14.

A terminal 62 a of the switch 62 is connected to the input terminal IN2.Thus, a descrambled TS is supplied from the descrambler 12 to the switch62 through the input terminal IN2. The switch 62 is connected to a PIDextracting portion 71 of the data parser portion 70. The switch 62selects one of the terminals 62 a and 62 b under the control of thecontroller 14. Alternatively, the switch 62 selects neither the terminal62 a nor 62 b under the control of the controller 14.

The switch 63 is connected to the input/output terminal IN/OUT. Theswitch 63 selects one of the terminals 63 a and 63 b under the controlof the controller 14. An output signal of a parser 74 of the data parserportion 70 is supplied to the terminal 63 a.

The data parser portion 70 is composed of the PID extracting portion 71,a comparing portion 72, a register portion 73, and the parser 74. Thedata parser portion 70 extracts only a required TS packet from a TSreceived from the switch 62 and supplies the extracted TS packet to theterminal 63 a.

In other words, the PID extracting portion 71 directly outputs a TSreceived from the switch 62 to the parser 74. In addition, the PIDextracting portion_71 detects a PID from each TS packet that composesthe TS and supplies the PID to the comparing portion 72. The comparingportion 72 compares the PID stored in the register portion 73 with thePID received from the PID detecting portion_71. When they match, thecomparing portion 72 supplies a match signal to the parser 74. Theregister portion 73 stores the PID received from the controller 14through the control bus 16. In other words, in the case that the userrecords only a broadcast program of a desired channel to the DVCR 7,when he or she designates the channel, the controller 14 supplies a PIDof a TS packet corresponding to the channel to the register portion 73through the control bus 16. The register portion 73 stores the PIDreceived from the controller 14. The register portion_73 can store aplurality of PIDs.

The parser 74 extracts a TS packet from the TS received from the PIDextracting portion 71 corresponding to the match signal received fromthe comparing portion (namely, a TS packet with the same PID as the PIDstored in the register portion 73) and supplies the extracted TS packetto the terminal 63 a. The TS packets that have not been extracted by theparser 74 are discarded.

Next, the operations of the switching portion 21 corresponding to thenormal mode, the descramble output mode, the non-descramble output mode,and the input mode will be described. In this example, it is assumedthat a particular PID has been assigned to the register portion 73 bythe controller 14.

In each mode, the controller 14 controls the switches 61 to 63 to selectrespective terminals as shown in FIG. 9.

Thus, in the normal mode, the switch 61 selects the terminal 61 a; theswitch 62 selects neither the terminal 62 a nor terminal 62 b(hereinafter, this state is referred to as the free state); and theswitch 63 is in a don't care state (namely, the switch 63 selects eitherthe terminal 63 a or the terminal 63 b). Consequently, a non-descrambledTS received from the front end portion 11 to the terminal 61 a throughthe input terminal IN1 is directly supplied from the output terminal OUTto the descrambler 12 through the switch 61.

In the descramble output mode, as shown in FIG. 9, the switch 61 selectsthe terminal 61 a; the switch 62 selects the terminal 62 a; and theswitch 63 selects the terminal 63 a.

Thus, as in the normal mode, a non-descrambled TS received from thefront end portion 11 to the terminal 61 a through the input terminal IN1is directly supplied from the output terminal OUT to the descrambler 12through the switch 61.

The descrambler 12 descrambles the non-descrambled TS received from theoutput terminal OUT and supplies a descrambled TS to the terminal 62 athrough the input terminal IN2. Since the switch 62 selects the terminal62 a, the descrambled TS received through the, terminal 62 a is suppliedto the PID extracting portion_71 through the switch 62.

The PID extracting portion 71 directly supplies a TS received from theswitch 62 to the parser 74. In addition, the PID extracting portion 71detects a PID from each TS packet that composes the TS and supplies thePID to the comparing portion 72. The comparing portion 72 compares thePID stored in the register portion 73 with the PID received from the PIDextracting portion 71. Only when they match, the comparing portion 72supplies a match signal to the parser 74.

When the parser 74 receives the match signal from the comparing portion72, the parser 74 extracts a TS packet corresponding to the match signal(namely, a TS packet with the same PID as the PID stored in the registerportion 73) (hereinafter, this TS packet is referred to as a matchpacket), removes the other TS packets, and outputs the match packet tothe terminal 63 a.

In this case, the parser 74 outputs match packets to the terminal 63 aat intervals of a predetermined time period. When the relative timeperiod between the match packets is lost, it is difficult to MPEG-decodethem.

Since the switch 63 selects the terminal 63 a, a match packet receivedfrom the parser 74 is supplied to the IEEE 1394 interface 22 through theswitch 63 and the input/output terminal IN/OUT. The IEEE 1394 interface22 converts the format of the match packet (in this case, a descrambledTS packet) received from the switching portion 21 corresponding to theIEEE 1394 standard and transmits the converted signal to the DVCR 7.

At this point, as described above, the controller 14 transmits therecord AV/C command to the DVCR 7 through the IEEE 1934 interface. Thus,the DVCR 7 records data received from the IEEE 1934 interface 22.

In this case, a match packet sequence received from the parser 74 hasblank portions because TS packets other than match packets have beenremoved. Thus, the match packet sequence should be arranged so thatother units can properly process it. To arrange the match packetsequence, for example, a PAT, a PMT, an SIT (Selection InformationTable), and a DIT (Discontinuity Information Table) are added. Thus, thecontroller 14 generates a PAT, a PMT, an SIT, and a DIT and suppliesthem to the IEEE 1394 interface 22 through the control bus 16. The IEEE1394 interface 22 places the PAT, PMT, SIT, and DIT as TS packets at theblank portions of the match packet sequence and transmits the resultantsequence as a partial transport stream (hereinafter referred to as apartial TS) to the DVCR 7.

For details of the PAT, the PMT, the SIT, and the DIT, refer to forexample ETS 300468, Digital Video Broadcasting (DVB): Specification forService Information (SI) in DVB system.

As shown in FIG. 9, in the non-descramble output mode, the switch 61selects the terminal 61 a; the switch 62 selects the terminal 62 b; andthe switch 63 selects the terminal 63 a.

Thus, a non-descrambled TS received from the front end portion 11 to theterminal 61 a through the input terminal IN1 is supplied to the terminal62 through the switch 61. In this case, since the switch 62 selects theterminal 62 b, a non-descrambled TS is supplied to the PID extractingportion 71 through the switch 62.

Thereafter, the same process as the descramble output mode is performed.Thus, a non-descrambled TS is transmitted and recorded to the DVCR 7.

In the input mode, as shown in FIG. 9, the switch 61 selects theterminal 61 b; the switch 63 selects the terminal 63 b; and the switch62 is in a free state.

In this case, the controller 14 transmits the reproduction AV/C commandto the DVCR 7 through the IEEE 1394 interface 22. Thus, the DVCR 7starts the reproducing operation and transmits the reproduced data tothe IEEE 1394 interface 22.

The IEEE 1394 interface 22 converts the IEEE 1394 format of datareproduced from the DVCR 7 into the format of the original TS (in thiscase, partial TS) and supplies the partial TS to the switch 63 throughthe input/output terminal IN/OUT. As described above, since the switch63 selects the terminal 63 b, the TS received from the IEEE 1394interface 22 is supplied to the terminal 61 b through the switch 63 andthe terminal 63 b.

As described above, since the switch 61 selects the terminal 61 b, theTS received through the terminal 63 b is supplied to the output terminalOUT through the switch 61. Since the switch 62 is in the free state, theTS that is output through the switch 61 is not supplied to the PIDdetecting portion 71.

The TS that is output from the output terminal OUT is supplied to thedescrambler 12. When necessary, descrambler 12 descrambles the TS andsupplies the descrambled TS to the decode portion 13.

The IEEE 1394 interface 22 converts data received from the datainterface 20 into isochronous packets and isochronously transmits themto the DVCR 7. In addition, the IEEE 1394 interface 22 converts acommand for the DVCR 7 into an asynchronous packet corresponding to IEEE1394-1995 standard and asynchronously transmits it to the DVCR 7.Moreover, the IEEE 1394 interface 22 receives isochronous data, anasynchronous command, a status, and so forth from the DVCR 7 andtransmits them to relevant blocks such as the controller 14.

As described above, the IRD 5 has the switching portion 21 that suppliesa non-descrambled TS received from the front end portion 11 or adescrambled TS (descrambled data) received from the descrambler 12 tothe DVCR 7 and that supplies data received from the DVCR 7 to thedescrambler 12. Thus, both a non-descrambled TS and a descrambled TS canbe output to the DVCR 7. In addition, when necessary, data reproducedfrom the DVCR 7 can be descrambled and MPEG-encoded. In other words,with the IRD 5, data can be flexibly input and output.

In addition, since a TS received from the front end portion 11 is outputfrom the output terminal OUT through the switch 61 and supplied to theterminal 62 b, while the user is viewing a particular broadcast program,it can be output to and recorded by the DVCR 7 as an external unit.

In addition, since the IEEE 1394 interface 22 is disposed as aninterface between the switch portion 21 and the DVCR 7, while TS packetsare being exchanged with an external unit, AV/C commands can be alsoexchanged. Moreover, when the IRD 5 is connected to a high speed IEEE1394 network, a TS can be transmitted and received to/from a unitconnected to the IEEE 1394 network.

In addition, with the switching portion 21 and the IEEE 1394 interface22, the user is provided with an intelligent service using GUI(Graphical User Interface) of the IRD 5. In other words, when a TS isreproduced from the DVCR 7 and the TS is decoded and displayed by theIRD 5, the IEEE 1394 interface 22 receives a status that representswhether or not the DVCR 7 is correctly reproducing data. When the DVCR 7is not correctly reproducing data, the controller 14 allows the switches61 to 63 not to select any terminals. Thus, abnormal data can beprevented from being input to the descrambler 12 and the decode portion13. Thus, an abnormal picture can be prevented from being displayed.

In this case, with the GUI of the IRD 5, a message that represents thatdata cannot be normally reproduced can be output to the user.

In addition, the data parser portion 70 of the switching portion 21extracts only TS packets of a desired channel and outputs the extractedTS packets to an external unit. Thus, when a broadcasting stationtransmits scenes photographed at a plurality of angles in one programwith a plurality of channels of a frequency band of one transponder, theuser can record only scenes photographed at a desired angle.

In the above-described embodiment, the present invention was applied toa broadcasting system that transmits digital broadcast programs througha satellite. However, the present invention can be applied to digitalbroadcasts using for example a CATV network, Internet, a ground line,and other communication mediums.

In the above-described embodiment, the IEEE 1394 interface 22 isdisposed as an interface between the switching portion 21 and the DVCR7. An interface other than the IEEE 1394 interface 22 may be used. Inaddition, a parallel interface rather than a serial interface may beused.

In the above-described embodiment, the DVCR as an external unit isconnected to the IRD 5. However, the external unit connected to the IRD5 is not limited to the DVCR.

In the above-described embodiment, the switching portion 21 extractsparticular TS packets from a TS and records the extracted TS packets tothe DVCR 7. Alternatively, the entire TS may be supplied and recorded tothe DVCR 7.

In the above-described modifications, digital data received from theDVCR is supplied to the descrambler through the IEEE 1394 interface.When the digital data has been scrambled, it is descrambled by thedescrambler. When the digital data has not been scrambled, it isdirectly supplied to the decoder. Alternatively, only when digital datareceived from the DVCR has been scrambled, the digital data may besupplied to the descrambler. When the digital data has not beenscrambled, the digital data may be directly supplied to the decoder.

As described above, according to the input/output unit, the receivingunit, and the input/output method of the present invention, digital datathat is received from the receiving means or descrambled data that isreceived from the descramble means is supplied to an external unit. Inaddition, data that is received from an external unit is supplied to thedescramble means of the receiving unit. Thus, digital data can beflexibly input and output.

What is claimed is:
 1. An input/output unit for managing data that isinput and output between a receiving unit and an external unit, thereceiving unit having receiving means for receiving digital data thathas been at least partly scrambled and descramble means for descramblingdigital data to form descrambled data, the input/output unit comprising:input/output controlling means for supplying the received digital dataor the descrambled data to the external unit and for supplying datareceived from the external unit to the descramble means; and aninterface between said input/output controlling means and the externalunit; said input/output controlling means including: extracting meansfor extracting only predetermined data from the received digital data orthe descrambled data, and for outputting the extracted data to saidinterface; first selecting means for selecting one of the receiveddigital data and the data received from the external unit as firstselected data, and for supplying the first selected data to thedescramble means; second selecting means for selecting one of thereceived digital data and the descrambled data as second selected data,and for supplying the second selected data to said extracting means; andthird selecting means for selecting one of the extracted data from saidextracting means and the data received from the external unit as thirdselected data, for supplying the third selected data to the externalunit when the third selected data is the extracted data from saidextracting means, and for supplying the third selected data to thedescramble means when the third selected data is the data received fromthe external unit.
 2. The input/output unit as set forth in claim 1,wherein when the first selected data supplied to the descramble meansfrom said input/output controlling means has been scrambled, thedescramble means descrambles the first selected data, and when the firstselected data supplied to the descramble means from said input/outputcontrolling means has not been scrambled, the descramble means does notdescramble the first selected data.
 3. The input/output unit as setforth in claim 1, wherein the received digital data and the descrambleddata include a plurality of packets, and said extracting means extractsonly predetermined packets from the plurality of packets forming thereceived digital data or the descrambled data, and supplies theextracted packets to said interface so that each of the extractedpackets retains its relative time period.
 4. The input/output unit asset forth in claim 1, wherein the descramble means determines whether ornot the digital data has been scrambled based on scramble stateinformation contained in the digital data.
 5. The input/output unit asset forth in claim 1, wherein said interface processes the extracteddata from said extracting means so that the external unit normallyprocesses the extracted data from said extracting means.
 6. Theinput/output unit as set forth in claim 1, wherein the received digitaldata and the descrambled data include a plurality of packets; and saidextracting means includes: detecting means for detecting packetidentification information from the plurality of packets forming thereceived digital data or the descrambled data; storing means for storingthe packet identification information of at least one of the pluralityof packets to be extracted; comparing means for comparing the packetidentification information detected by said detecting means with thepacket identification information stored in said storing means; andsupplying means for supplying an extracted packet to said thirdselecting means, the packet identification information of the extractedpacket corresponding to the packet identification information stored insaid storing means.
 7. A receiving unit, comprising: receiving means forreceiving digital data that has been at least partly scrambled;descrambling means for descrambling digital data to form descrambleddata; input/output controlling means for supplying the received digitaldata or the descrambled data to an external unit and for supplying datareceived from the external unit to said descramble means; and aninterface between said input/output controlling means and the externalunit; said input/output controlling means including: extracting meansfor extracting only predetermined data from the received digital data orthe descrambled data, and for outputting the extracted data to saidinterface; first selecting means for selecting one of the receiveddigital data and the data received from the external unit as firstselected data, and for supplying the first selected data to saiddescramble means; second selecting means for selecting one of thereceived digital data and the descrambled data as second selected data,and for supplying the second selected data to said extracting means; andthird selecting means for selecting one of the extracted data from saidextracting means and the data received from the external unit as thirdselected data, for supplying the third selected data to the externalunit when the third selected data is the extracted data from saidextracting means, and for supplying the third selected data to saiddescramble means when the third selected data is the data received fromthe external unit.
 8. The receiving unit as set forth in claim 7,wherein when the first selected data supplied to said descramble meansfrom said input/output controlling means has been scrambled, saiddescramble means descrambles the first selected data, and when the firstselected data supplied to said descramble means from said input/outputcontrolling means has not been scrambled, said descramble means does notdescramble the first selected data.
 9. The receiving unit as set forthin claim 7, wherein the received digital data and the descrambled datainclude a plurality of packets, and said extracting means extracts onlypredetermined packets from the plurality of packets forming the receiveddigital data or the descrambled data, and supplies the extracted packetsto said interface so that each of the extracted packets retains itsrelative time period.
 10. The receiving unit as set forth in claim 7,wherein said descramble means determines whether or not the digital datahas been scrambled based on scramble state information contained in thedigital data.
 11. The receiving unit as set forth in claim 7, whereinsaid interface processes the extracted data from said extracting meansso that the external unit normally processes the extracted data fromsaid extracting means.
 12. The receiving unit as set forth in claim 7,wherein the received digital data and the descrambled data include aplurality of packets; and said extracting means includes: detectingmeans for detecting packet identification information from the pluralityof packets forming the received digital data or the descrambled data;storing means for storing the packet identification information of atleast one of the plurality of packets to be extracted; comparing meansfor comparing the packet identification information detected by saiddetecting means with the packet identification information stored insaid storing means; and supplying means for supplying an extractedpacket to said third selecting means, the packet identificationinformation of the extracted packet corresponding to the packetidentification information stored in said storing means.
 13. Aninput/output method for inputting and outputting data between areceiving unit and an external unit, the receiving unit being operableto receive digital data that has been at least partly scrambled, theinput/output method comprising the steps of: selecting one of thereceived digital data and data received from the external unit as firstselected data; descrambling the first selected data to form descrambleddata; selecting one of the received digital data and the descrambleddata as second selected data; extracting only predetermined data fromthe second selected data to form extracted data; outputting theextracted data to the external unit; and selecting one of the extracteddata and the data received from the external unit as third selecteddata, supplying the third selected data to the external unit when thethird selected data is the extracted data, and descrambling the thirdselected data when the third selected data is the data received from theexternal unit.
 14. A system for managing data, comprising: a receivingunit having receiving means for receiving digital data that has been atleast partly scrambled and descramble means for descrambling digitaldata to form descrambled data; an external unit; input/outputcontrolling means for supplying the received digital data or thedescrambled data to said external unit and for supplying data receivedfrom said external unit to said descramble means; and an interfacebetween said input/output controlling means and said external unit; saidinput/output controlling means including: extracting means forextracting only predetermined data from the received digital data or thedescrambled data, and for outputting the extracted data to saidinterface; first selecting means for selecting one of the receiveddigital data and the data received from said external unit as firstselected data, and for supplying the first selected data to saiddescramble means; second selecting means for selecting one of thereceived digital data and the descrambled data as second selected data,and for supplying the second selected data to said extracting means; andthird selecting means for selecting one of the extracted data from saidextracting means and the data received from said external unit as thirdselected data, for supplying the third selected data to said externalunit when the third selected data is the extracted data from saidextracting means, and for supplying the third selected data to saiddescramble means when the third selected data is the data received fromsaid external unit.